In response to the environmental protection requirements, bioplastics are increasingly adopted. Bioplastics are plastics made from natural materials, such as starches of corn, sugar beet, wheat, sweet potato, etc., or sugar, which are fermented, dehydrated and polymerized to make into polymers. Because the polylactic acid (PLA) in the natural materials is degradable under certain conditions, harm to the environment can be avoided. Further, by using the injection molding machine, tablewares, such as plates, cups, bowls, knives, forks, etc., made from bioplastics can be mass produced. However, the existing injection molding machine used for making a product from the bioplastics has the disadvantages of slow crystallization rate and low production efficiency.
To solve the aforesaid problems, a conventional bioplastic injection molding mechanism has been proposed, which is disclosed in Taiwanese Patent No. I403405. The bioplastic injection molding mechanism includes an injection molding machine, a liquid temperature circulation mechanism and an electromechanical control interface electrically connecting the injection molding machine and the liquid temperature circulation mechanism. The injection molding machine has a machine platform provided with a fixed mold seat, a movable mold seat, a toggle mechanism to drive the movable mold seat toward and away from the fixed mold seat, and a pushing mechanism. A mold has a female mold fixed to the fixed mold seat, and a male mold fixed to the movable mold seat. The liquid temperature circulation mechanism is connected to the male and female molds, and has a cold source device and a heat source device.
Although the aforesaid conventional bioplastic injection molding mechanism can achieve its intended purpose, after injection of materials into the mold, the cold source device must first be activated to cool the mold. After the temperature of the mold drops to a predetermined value, the heat source device is then activated to heat the mold. That is, the aforesaid single mold is repeatedly cooled and heated on the same workstation. As such, not only is the operation time long, but also the energy is wasted due to cooling of the mold by the cold source device and then heating of the mold by the heat source device.